HPV is superior to aHP for inactivation of microbial contamination, study finds

Hydrogen peroxide vapour (HPV) technology is confirmed as superior to the aerosolised hydrogen peroxide (aHP) process following the publication of an independent study.

A team at St George’s Hospital, Tooting, UK, established that HPV technology from Bioquell was faster, safer and more effective for biological inactivation than aHP.

Incomplete inactivation of microbial contamination is a risk in hospitals because the remaining microorganisms can be transmitted to other patients. The study assessed the inactivation of specific organisms known to cause healthcare associated infections (HCAIs), such as Clostridium difficile, Acinetobacter baumannii and MRSA.

The Bioquell HPV system was significantly more effective at inactivating the microorganisms than the aHP system (now supplied as a Glosair from Advanced Sterilization Products (ASP)). Test discs containing the microbes situated around corners, out of direct line of sight of the aHP machine, were left active. The aHP system failed to inactivate MRSA or A. baumannii dried from suspension in water at any of the locations assessed.

Both systems were tested using 6-log and 4-log biological indicators (BIs) distributed throughout the test area, which are the standard used to validate decontamination processes.

Bioquell’s HPV technology demonstrated almost complete inactivation of 6-log and 4-log BIs. This compared with inactivation of <15% of the 6-log BIs by the aHP technology and one third of the 4-log BIs. It was determined that poor hydrogen peroxide distribution associated with the aHP process compared with the complete dispersal of the HPV was one of the reasons for the poor inactivation results.

To assess the speed of each cycle, a comparison of hydrogen peroxide concentration levels in the room after 2 hours was also made for both systems. Here, the HPV system had a lower hydrogen peroxide level (1.3ppm) compared with the aHP hydrogen peroxide level (2.8ppm) at the 2hr cycle mark, demonstrating faster cycle times.

The study also called into question the safety of the aHP system. According to the aHP manufacturer’s instructions at the time, the room did not need to be sealed with tape and was safe to enter after 2 hours. However, the report stated that both these protocols were found to expose operators to unsafe levels of hydrogen peroxide. In contrast, no health and safety issues were found with the Bioquell system. Here it was recommended that the room was sealed and the manufacturer supplied hydrogen peroxide sensors to ensure levels were safe at re-entry.

Commenting on the report, James Salkeld, head of Bioquell Healthcare, said: “I am pleased that this study reinforces the superior efficacy and speed of the Bioquell technology. In my view, the reason for moving to a high-tech, automatic system is to ensure you eliminate all pathogens, every time, and this study re-states Bioquell’s credentials as the only technology that can achieve this.”

The study was published in the Journal of Hospital Infection, February 2012 and compared a Bioquell HPV generator with a Sterinis aHP generator (now supplied as a Glosair from Advanced Sterilization Products (ASP)). The room volume was 50m3 with a 13m3 annex.